The attached simplifies the code handling lval_register by exploiting 
the assumption:

     /* In a register.  Registers are relative to a frame.  */
     lval_register,

i.e., there's always a frame.  With just that committed, my PPC results 
regress.  It turns out that the value code was forgetting to propogate 
the value id.  A sequence like:

	(gdb) up
	(gdb) set variable u.i = 1

where "u" was in a register in frame #1 would end up trashing the 
corresponding register in frame #0.

committed,
Andrew